These results on the Hecke eigenvalues of genus 2 forms
stimulated Harder to formulate a precise conjecture
on congruences between elliptic
modular forms and Siegel modular forms, see [1]}.
For a long time he had suspected that there should be such conguences.
Our work provided strong evidence for
this conjecture.
For me such results beautifully show the use of counting points
over finite fields.
